1. Field of the Invention
This invention relates to a vent closure member formed of a closed cell, air impermeable backing member and air permeable foam members, to close the gap between metal or other roofing panels and a v-shaped ridge vent cover, in order to permit air circulation but prevent entry of wind driven rain and insects.
2. Description of the Prior Art
Metal roofing has become an accepted material that provides a high quality and long lasting roof. Numerous manufacturers of metal roofing panels will typically each have some unique difference in the profile of their own metal panel. Each manufacturer therefore has their own specialized signature profile. The profile of the metal roof when viewed from the end leaves openings that might allow for the penetration by wind driven precipitation, or openings through which birds, insects and other creatures can gain entrance into a roofing system. Closing these gaps has been necessary to prevent the intrusion of foreign debris, acoustic energy, and precipitation from gaining entrance to the roofing system.
The manufacture of gaskets or closure strips used to cover the gaps has been widely used since the 1970's. These gaps and voids need to be filled in order to have an effective roof system. Materials used to close these gaps and voids are known as closure strips. Historically rubber materials including ethylene propylene diene monomer (EPDM) and vinyl nitrile were used in the construction of metal buildings and metal roofing as closure strips to prevent water and insects from penetrating the joints of the metal building. In the 1970's it was discovered that polyethylene foam could perform similarly to the EPDM and vinyl nitrile products previously employed for closure strips. The polyethylene worked well because it was closed cell and was light weight (2 lb/ft.3), but had problems with oxidation and premature aging. The preferred material in the industry became crosslinked polyethylene which didn't have the oxidation problem that linear polyethylene had. One of the major disadvantages of using crosslinked polyethylene, however, was availability from manufacturers, from whom it could not be reliably purchased. Production in other markets often limited the availability of crosslink polyethylene in the metal building markets. The substitution of alternate materials has therefore been under investigation for some time. Substitute materials that have been investigated to overcome physical short comings of the cross linked polyethylene, which included that fact that it is non recyclable which adds to manufacturing costs; cross linked polyethylene had no UV stabilizer, which would help to extend the life span of the product; the original Crosslink product had no fire resistant properties; and the crosslink product had substantial shrinkage problems at elevated temperatures, which allowed the ready passage of rain water and insects. Typical metal roof temperatures during warmer months will reach 180° Fahrenheit, and can even reach 200° Fahrenheit on extremely warm days.
Initial development resulted in a material known as “Soft cell”, which matched the physical performance characteristics of the crosslink closure, had UV stabilization, had F/R, was micro cellular, and was recyclable. A second iteration of material was called GF-1, which exceeds the physical characteristics of crosslink polyethylene in compressive strength, thermal stability, UV resistance, tear resistance, thermal stability, and density, Both products were marketable, as manufacturing costs to produce the GF-1 strips were lower than that of crosslink polyethylene. While they both performed well for the application, and had significant advantages over the crosslink polyethylene, the base resin was linear polyethylene, and at elevated temperatures seen on most buildings as high as 200° F., crosslinked and linear polyethylene were limited in their capability. The low level of thermal stability for both crosslinked and linear polyethylene caused them to shrink at the high temperature levels. It was at this point a third iteration was investigated that would not only continue to exhibit the UV stability, recyclability, compressive strength, F/R, tear resistance, but would also have thermal stability at higher temperatures which would not show signs of shrinkage. This approach involved foaming polypropylene which as a base resin has a greater heat resistance as high as 280° F., which is in excess of the requirements of metal roofing and metal buildings.
U.S. Pat. No. 8,276,331 discloses a sealant strip that can be located between a roof and a ridge cap. That device has an air impermeable section that is cut to engage the contoured surface of the roof, such as the ridges or protrusions on a metal roofing panel. A series of rectangular air permeable members engage the flat lower surface of the ridge cap. In that device, the air permeable members are less dense than the air impermeable members.